ES2903075T3 - Recyclable and refillable translucent or transparent paper for use in packaging applications - Google Patents

Abstract

A translucent or transparent paper comprising: (i) a fibrous substrate having a front side and a back side, the fibrous substrate comprising cellulose fibers refined to above 40°SR and the opacity number of said fibrous substrate being less 45% or more measured in accordance with ISO 2471; and (ii) one or more coating layers, in particular one or two coating layers arranged on the front side of said fibrous substrate, comprising a material chosen from a material that imparts moisture barrier properties and has the ability to of transparency when provided as a coating layer on said fibrous substrate and allowing the translucent or transparent paper to be repastable, said material being chosen from the group comprising or consisting of vinylidene chloride copolymer or homopolymer, styrene copolymer or homopolymer , such as styrene 1,3-butadiene polymer, acrylic copolymer or homopolymer, polyester or paraffin copolymer or homopolymer, such as paraffin wax.

Description

DESCRIPTION

Recyclable and refillable translucent or transparent paper for use in packaging applications

field of invention

The present invention relates to translucent or transparent paper suitable for laminating and packaging applications. More particularly, the present invention relates to a translucent paper having improved transparency through a coating process. Said transparent or translucent paper serves as a recyclable, repastable and renewable alternative to plastic wrappers and laminates.

The invention also relates to a process for the manufacture of a transparent or translucent paper and to the use of the obtained paper in various domains, including the packaging of any type of goods, such as consumer goods or food products.

The translucent or transparent paper of the invention comprises a fibrous substrate comprising cellulose fibers refined to above 40 °SR and having an opacity of less than or equal to 45% measured in accordance with ISO 2471, preferably a paper for natural tracing (ie a tracing paper prepared from highly refined cellulose fibers) and a coating layer disposed (coated) on said fibrous substrate. Said coating layer enhances the transparency of the fibrous substrate, while also providing good moisture barrier properties.

In one aspect, one or more coating layers are disposed on both the leading and trailing sides of the fibrous substrate. The coating layer(s) arranged on the front side and the back side of the fibrous substrate may or may not be of the same nature. The resulting translucent or transparent paper can be used as a wrapper on an article, such as consumer goods or food products.

In another aspect, the back side of the fibrous substrate comprises a printed feature.

The printed feature is laterally inverted when viewed from the back side of the fibrous substrate and can be read from left to right when viewed from the front side of the fibrous substrate, through the cover layer(s) and the fibrous substrate . One or more layers of white ink may be disposed over the printed feature on the back side of the fibrous substrate in order to enhance the contrast of the printed feature.

The present invention further discloses a product comprising said translucent or transparent paper, wherein said translucent or transparent paper is glued, through a layer of glue or adhesive, to a paper or light cardboard/cardboard support, for example , in the form of an article of any shape and size, and therefore said translucent or transparent paper covers said support at least in part, for example, its external surface or its internal surface and possibly its entire surface.

The present invention also relates to a method of producing said translucent or transparent paper and to a method of producing said product comprising said translucent or transparent paper.

The use of said translucent or transparent paper for packaging, especially luxury packaging, in order to wrap, contain or laminate objects is also disclosed. Such packaging encompasses boxes or closed containers that protect, identify and transport a wide range of goods, including food and consumer products. Accordingly, the transparent or translucent paper of the invention can be provided in any format suitable for packaging, such as sheets or wrappers, which are flat, rolled or folded. Consequently, the paper of the invention acts as a protection for the element (whether liquid or solid) that makes contact with, surrounds or contains or as a cover that allows said element to be observed through the paper due to its transparency. In particular, the paper of the invention may serve the purpose of protecting the article it contacts, surrounds, contains or covers against scratches, fingerprints, oil/water stains, oxygen and other contaminants. Unlike most of the packaging materials known in the art, the paper of the invention is not prepared from or contains plastic film and, additionally, it can have a smooth surface that avoids abrasions and allows color and touch effects. Background of the invention

Packaging materials, such as wrappers, are used to protect items from external influences and contaminants, such as scratches, fingerprints, as well as oil and water stains. Petroleum-based plastics, in particular plastic films, are the most popular packaging material due to their low weight, flexibility, durability, transparency, versatility, as well as chemical stability.

Paper and plastic film laminates are also often used in the packaging of things, such as boxes and bags, especially in luxury goods.

Unfortunately, most plastics today are made from non-renewable carbon sources and pose environmental concerns. Also, these are not easily recycled. Therefore, plastics do not provide a solution for companies seeking recyclability, environmental sustainability and refillability of packaging materials.

To this end, the two important actions needed in the packaging industry are: firstly, the use of renewable raw materials and, secondly, the possibility of recovery and recycling of used packaging materials.

Environmental concerns prompted the development and use of non-petroleum derived plastic films, such as PE films made from bioethanol. Although these plastic materials are renewable, they are difficult to recycle once they are laminated into lightweight cartons.

There are also plastics synthesized through the green chemistry route. For example, plant-based polylactic acid (PLA) derived from cornstarch, such as one developed by Toray, is gaining popularity as an alternative to petroleum-based plastics. This material is renewable and recyclable, but once it is laminated into a lightweight cardboard, it is difficult to recycle.

European patent EP3087129 describes biodegradable plastics that degrade into low molecular weight oligomers or monomers through the use of enzymes. Such plastics are recyclable, but not necessarily renewable, and once laminated into lightweight paperboard, they are difficult to recycle.

US Patent No. 4,569,888 teaches transparent paper by impregnation of polymers within the fibrous network and crosslinking in situ. The process leads to a highly transparent paper that is recyclable and refillable. However, the oil and gas barrier properties of the paper, as well as the possibility of further enhancing the transparency of such paper after the papermaking process by simple means, are not anticipated.

The inventors have advantageously designed a paper-based packaging material as an alternative to plastics used as wrappers or laminating films. Said paper-based packaging material is prepared from a renewable resource and is recyclable.

Therefore, the paper of the invention solves the problem faced by the prior art, which is to devise a recyclable and refillable solution to replace prepared plastic packaging materials, in particular plastic films. Furthermore, the paper of the invention surprisingly offers a transparent or translucent paper having improved transparency compared to known translucent paper, especially tracing paper, which also exhibits dimensional stability and barrier properties against external aggressions. Furthermore, such paper exhibits additional printing capabilities, since it allows printing on the back side (or rear side) of the paper, as an alternative to or in addition to printing on the front side (or front side) when used. Furthermore, it may have a tactile effect, such as a soft touch effect.

The physical structure of a paper allows for approximately 40% light scattering from the top surface of the paper, approximately 2o% light scattering from the thickness of the paper, and approximately 40% light scattering from the surface. bottom of the paper, which add up to give 100% opacity. Therefore, by reducing the amount of light scattering, transparency is gained.

The invention discloses a sheet of paper that becomes more translucent or transparent than commonly known tracing papers. Up to 20% transparency (or up to 20% light scattering ability reduced) can be gained during the papermaking process, for example by reducing air/cellulose fiber interfaces or the porosity within the thickness of the paper. Up to 40% transparency is gained by applying a coating to the top surface of the paper, and similarly, up to 40% transparency is gained by applying a coating (of the same or different nature as the top surface) onto the bottom surface of the paper. The coating applied to the top or bottom surface of the paper reduces the light scattering ability by reducing surface irregularities and/or by reducing surface inhomogeneity present due to an index mismatch. refraction between air bubbles and cellulose fibers. The present invention relates to transparency by coating on the surface of a fibrous substrate, in particular a sheet of translucent paper, as opposed to transparency which would occur by impregnation of said fibrous substrate. Consequently, the coating layer does not substantially penetrate the fibrous substrate, especially no deeper than filling in the irregularities/roughnesses of the surface of said fibrous substrate. Therefore, the coating layer does not impregnate the fibrous substrate. In other words, the techniques applied to deposit the layer are conventional techniques which lead to a short time scale of contact between the fibrous substrate and the coating composition before it begins to dry. This time scale is typically less than 10 seconds or even less than 5 seconds.

The inventors have surprisingly observed that the coating layer(s) can be defined and provide to achieve an enhanced transparency of a translucent paper used as a substrate, in particular, a natural tracing paper, while creating the moisture barrier property at the same time. In addition, the inventors have found that the addition of the moisture barrier property in the coating layer greatly reduced the coefficient of hygroexpansion of the translucent paper and consequently obtained an unexpected level of improvement in the dimensional stability of said paper. translucent or transparent paper, especially that prepared from natural tracing paper with highly refined cellulose fibers. Furthermore, the transparency of the translucent paper by applying the coating layer(s) allowed a feature to be printed on the back side of the translucent or transparent paper in a reverse mode so that the printed feature was read from the front side. of such translucent or transparent paper, while protecting it from moisture, oxygen, grease and other environmental factors.

The present invention is defined by the claims.

Advantageously, the invention may, in addition to the properties disclosed above, allow the roughness (Bendtsen roughness) of the fibrous substrate to be reduced when the coating layer has been applied on said substrate. This additional result can be obtained depending on the coating process used. As a result, the roughness of the coated face(s) may be less than 120 ml/min, in particular it may be in the range of about 70 ml/min.

The terms and expressions used in the present description and, in particular, for the definition of the particular embodiments and the examples, generally have a usual meaning for those skilled in the art. In addition, the following terms and expressions are given the particular meanings defined below. Such particular definition may be considered in conjunction with the usual meaning used by those skilled in the art.

The "translucent or transparent paper" of the present invention means a paper material or a paper object obtained from pulp fibers forming a fibrous substrate and provided as a flat element, in particular, as a thin flat element, such as a sheet of paper, having an opacity or transparency as disclosed herein, including in accordance with the particular embodiments of the Examples. The translucent or transparent paper of the present invention does not contain a plastic film and is therefore recyclable and/or repastable. Other specific features of the transparent or translucent paper of the invention are disclosed herein.

The term "opacity" describes the extent to which an object, in particular a sheet of paper, is seen through, since some light cannot travel through the object. Opacity can be considered inversely proportional to transparency. The opacity or transparency of a sheet of paper can be measured by apparatus known in the art, such as a NOVICOLOR N5950 spectrophotometer.

"Fibrous substrate", as used herein, refers to a material or article, in particular, a fibrous substrate-based sheet, in particular, a paper material or article, especially a paper sheet, and , generally, comprises vegetable fibres, cellulose fibres, in particular wood cellulose fibres, which are obtained especially from sustainable and environmentally friendly sources and processes. Advantageously, the fibrous substrate is translucent. Preferably, the fibrous substrate is a tracing paper, in particular a natural tracing paper. Natural tracing paper derives its translucency primarily from the unusually high degree of refinement given to the cellulose pulp fibers from which it is prepared. This results in a sheet without the air/fiber interfaces that give most papers their opacity. The translucency of natural tracing paper does not come from impregnation with an oil or other clear chemical. The natural tracing paper may be a modified natural tracing paper having improved folding strength, higher tear strength, higher stretchability under tensile loading before breakage, reduced tensile strength and reduced stiffness, such as a urea-treated natural tracing paper, as disclosed in European patent application EP1306484. Alternatives to a fibrous substrate consisting of tracing paper may include coated paper, vellum, impregnated paper, and parchment paper, or any paper substrate that has substantially transparent or translucent properties. Prepared tracing paper, such as that treated with sulfuric acid, can also be used as a translucent fibrous substrate.

According to the invention, at least one side of the fibrous substrate, as defined above and, in particular, when it consists of a tracing paper, is covered by a coating layer having a transparency property and/or properties. barrier, including a moisture barrier property. The other side of the fibrous substrate may be, in particular, a) glued to a light paper or board article, b) printed with a feature before sticking to a light paper or board article or c) covered with the same coating layer . In the case of c), the resulting translucent or transparent paper can be used as a sheet, band/strip/ribbon, or wrapper or any other suitable format of a translucent or transparent paper to replace plastic materials. The lightweight paper or paperboard article disclosed herein may comprise a printed feature, which may be covered (i.e., by gluing or lamination) by the transparent or translucent paper of the invention, such that the printed feature is protected from moisture, grease and mechanical abrasion, as long as it is visible through said transparent or translucent paper.

The terms " refillable paper" and " recyclable paper" refer to the ability to reuse paper as a raw material for the production of new paper. Different processes can be used to characterize this feature. In this document, reference is made to the term "Voluntary Regulation for the Refilling and Recycling of Corrugated Hardboard Treated to Improve Its Performance in the Presence of Water and Water Vapor", as revised on August 16, 2013.

The term "cover layer" refers to a dry or dried layer of material provided on at least the front side of the fibrous substrate by coating. The forward side of the fibrous substrate is the side that faces the user's manufacturer when viewed. The coating layer disposed on the front side of the fibrous substrate comprises a material which is suitable for providing barrier properties against moisture, oxygen and other gases, when coated on the fibrous substrate. The coating layer is additionally considered a "transparency layer" in that the coating advantageously alleviates surface irregularities or roughness of the fibrous substrate, thereby significantly reducing the amount of light that is removed by scattering. the surface of the fibrous substrate. The transparency property/function of the coating layer can also come from the reduced inhomogeneity of the surface present by the refractive index mismatch between the air bubbles and the fibrous fibers, in particular cellulose. In such a case, the refractive index of the coating layer is the same as or very close to that of cellulose fibers, thereby reducing the light scattering ability of the fibrous substrate. The coating layer can also penetrate into the fibrous substrate, thereby reducing any residual light scattering bound to the core/thickness of said fibrous substrate. The coating layer provided on the rear side of the fibrous substrate may or may not be of the same nature, but in any case it serves the purpose of making the fibrous substrate transparent in the manner described above. For example, an ink adhesion layer arranged on the back side can be considered a cover layer of a different nature, as long as it fulfills the purpose of making the fibrous substrate transparent in such a way as described above. However, unless otherwise stated, the coating layer provided on the rear side of the fibrous substrate is of the same nature (i.e., the same composition) as the coating layer provided on the front side of the fibrous substrate. . As long as the coating layer provided on the back side of the fibrous substrate is an ink-adhesive layer having an ink-adhesive property, it will be so clearly indicated.

The coating layer may comprise a textured surface that is haptically perceptible. This can be achieved by adding chemicals that change the coefficient of friction and/or particles that modify the roughness or smoothness of the surface according to the stiffness and size of the particles.

The coating layer may comprise materials that are not necessarily renewable. In such a case, the mass of the non-renewable material comprised in the coating layer is very low relative to the total mass of the cellulose fibers in the translucent or transparent paper. This allows the translucent or transparent paper to be repastable and/or recyclable.

Commercial products that can be used as a top coat include BASF's Epotal SP-106D (styrene 1,3-butadiene polymer aqueous dispersion), Schmid Rhyner's Galacryl 80.330.05 (acrylic polymer), Michelman's VaporCoat 2200 (acrylic polymer). acrylic), Akzo Nobel's Evcote 3050 (water-based polyester), SiOx deposition by vacuum deposition or atomic layer deposition (such as Armcor's Ceramis), Chromatogenie de Center Technique du papier Grenoble (fatty acid grafted onto the paper by gas chemical reaction), MYSTOLENE Ps from Catomance Technologies (paraffin wax and rosin) and AQUACER 497 from BYK Additives & Instruments (non-ionic aqueous emulsion of a paraffin wax).

Coating is performed according to any method well known in the art, such as roll-to-roll coating, knife coating, spray coating, Mayer rod coating, blow lip coating, direct gravure, lithographic print gravure, etc. Reverse gravure, deep coating, smooth roll coating, curtain coating, pearl coating, slot coating, double HSM coating, film press coating, size press coating and the transfer film method.

The term "exposed side" refers to one side of the coating layer, ink adhesion layer, primer layer, printed feature, or any other localized layer or deposit facing the fibrous substrate. In a particular embodiment, the exposed face may be the front side of the translucent or transparent paper.

The term "primer layer" refers to a dry or dried layer of material that is optionally provided below the cover layer in such a way that the primer layer is disposed or coated between the fibrous substrate and the cover layer with in order to improve the spreadability of the coating composition which subsequently forms the coating layer when it dries.

According to one embodiment of the invention, the optically transparent and electrically conductive material may be comprised within the cover layer (i.e. mixed in the composition of the cover layer). coating) or can form a sublayer of the coating layer.

The term "sublayer" refers to a layer that is provided together with another layer. When the cover layer comprises a sublayer of optically transparent and electrically conductive material, the sublayer of optically transparent and electrically conductive material may be disposed on the outermost face of the cover layer (i.e., away from or opposite the fibrous substrate). , below the cover layer (ie, in contact with the fibrous substrate or primer), or within the cover layer (ie, buried in or surrounded by the cover layer).

The optically transparent and electrically conductive material is optionally provided together with the coating layer and may form a continuous layer over a surface area of from a few square millimeters to tens of square centimeters. Such a continuous layer can serve as an electrode in applications such as photovoltaics.

The optically transparent and electrically conductive material is optionally arranged together with the coating layer and may form one or more continuous traces having a microscopic scale width, in particular a few micrometers, and a length in a range from a few micrometers. up to a few centimeters or tens of centimeters. In particular, this can be arranged as traces. Said one or more continuous traces can serve as antenna(s) in RFID or NFC applications.

The layer or trace(s) of optically transparent and electrically conductive material may be formed by various coating or printing techniques known to those skilled in the art, depending on the viscosity of such optically transparent and electrically conductive material provided or formulated by those skilled in the art.

The term "ink adhesion layer" refers to a layer that adheres an ink when a feature is required to be printed so that desired print quality can be achieved in various applications. The ink adhesion layer may alternatively be referred to as a "printable layer" or an "ink adhesion promoting layer". Advantageously, the ink adhesion layer is transparent. Preferably, the ink adhesion layer also acts as a "transparency layer" when applied to the back side of the fibrous substrate and alleviates surface irregularities or roughness of the fibrous substrate, significantly reducing the amount of light that is removed. by scattering from the surface of the fibrous substrate. Therefore, the ink adhesion layer can be considered a coating layer of a different nature. The ink adhesion layer may have refractive properties equal to or very close to those of cellulose fibers, thereby reducing the light scattering ability of the fibrous substrate. The ink adhesion layer can also penetrate into the fibrous substrate, thereby reducing any residual light scattering bound to the core/thickness of said fibrous substrate.

The ink adhesion layer can be disposed directly on the back side of the fibrous substrate or on a cover layer provided on the back side of the fibrous substrate.

"Printed feature" means any image or text printed in color or black and white, using various printing techniques, including, but not limited to, lithographic printing, inkjet printing, laser printing, xerographic printing, screen printing, flexo printing, continuous ink jet printing, liquid toner printing, letterpress, laser engraving and hot foil blocking.

The printed feature can be placed on the back side of the fibrous substrate in a variety of ways: (a) directly on the fibrous substrate, (b) on a cover layer that is disposed on the fibrous substrate or on a primer layer, or (c ) on an ink adhesion layer that is disposed on the fibrous substrate or on a coating layer.

The printed feature is advantageously printed in a reverse or mirror mode (ie left/right reversal) so that the printed feature can be read from the front side of the transparent fibrous substrate or translucent or transparent paper.

By printing on the back side of the fibrous substrate, it is possible for the printed feature to be protected from any external factors, such as moisture, oxygen, grease, and scratches.

The "white color ink" is advantageously disposed on the printed feature to cover the printed feature and preferably is disposed on the entire back side of the fibrous substrate. White ink increases the contrast of the printed feature, viewed from the front side of the fibrous substrate or translucent or transparent paper.

The invention also relates to a product comprising the translucent or transparent paper according to the invention glued by any available technique, in particular, laminated on a lightweight paper or cardboard article, such as a folded paper box and an assembled box , or a prepared case of light hard cardboard or a bag made of paper, light cardboard or cardboard.

The translucent or transparent paper of the invention can be glued to a conventional paper, board or light board (generally referred to as paper backing) printed with a feature through a layer of glue or adhesive disposed between the two.

The glue, which may be referred to as an adhesive, is used to adhere the translucent or transparent paper of the invention, which may or may not comprise a printed feature on the back side of the fibrous substrate, to any lightweight paper or paperboard article.

The glue or adhesive is preferably transparent or white in color and is applied in a continuous layer to ensure that no air bubbles or gaps are created between the translucent or transparent paper and the article or object to which the translucent paper is adhered or transparent. Advantageously, the glue or adhesive has a good moisture barrier property.

Additional features and details appear in the Examples that follow and in the Figure. Throughout the Examples, natural tracing paper was used to demonstrate specific embodiments of the invention.

Figure 1 discloses the moisture expansiveness of the coated tracing paper of Example 6 as measured by a Varidim apparatus.

examples

Example 1: A sheet of coated paper having a basis weight of 115 g/m2 (obtained from Satimat) was printed by xerography in black and a tracing paper was glued against the print with a two component polyurethane adhesive based on solvent containing ADCOTE 548-81R (from DOW EUROPE GmbH) and ethyl acetate. The gloss was measured with a NOVICOLOR N5950 spectrophotometer according to ISO 2469 through the tracing paper before and after the application of a top coat using a Mayer rod. Epotal SP-106D is an anionic dispersion of a styrene-butadiene copolymer, which provides a moisture barrier property. Galacryl 80.330.05 is a glossy acrylic varnish. Diofan A297 is an aqueous emulsion of polyvinylidene chloride. The values obtained are the following:

The lower the gloss, the darker the tone through the tracing paper. It was observed that the thinner the tracing paper, the lower the gloss. The gloss was lower after coating, except for the Epotal coating. Galacryl 80.330.05 and Diofan A297 improved the visibility of the printed feature.

Example 2: Three sheets of tracing paper sheets, each having a basis weight of 82 g/m2, 112 g/m2 and 180 g/m2, were printed by a Sakurai LED UV four color lithographic printing press and they were covered by a white color print applied by screen printing. The inks used were Xcura black, cyan, magenta and yellow. 100% ink coverage had ink densities between 1.2 and 1.5 for black, between 1 and 1.1 for cyan, between 0.9 and 1 for magenta, and between 0.8 and 0.9 in the case of yellow. A transparency layer was coated on the non-printed side by Mayer rod coating. Gloss measured at 100% black printing through paper is as follows:

The inventors observed that the gloss of the solid black color measured above was reduced when one of the coating compositions Diofan A297 or Epotal SP-103 D was applied. The printed feature was visually distinguishable through the tracing paper. The best result was obtained with the thinnest tracing paper (ie, the one with the lowest basis weight).

Example 3: The two sides of tracing paper sheets, each having a basis weight of 112 g/m2 and 80 g/m2, were coated with an adhesion promoter for liquid toner ink. These sheets were printed by liquid toner using an HP Indigo 7800 press. The 4 color image was covered by two layers of 100% white ink. The non-printed side was coated with a transparency layer by Mayer rod coating. The gloss measured at 100% black printing is as follows:

continuation

Example 4: A coating was applied to one side of a tracing paper having a basis weight of 52 g/m2 using a Mayer rod. On the one hand, a Galacryl 80.330.05 product was applied at a rate of 11.3 g/m2/s. On the other hand, 12.9 g/m2 of a Diofan A297 product was applied. The water vapor transmission rate was achieved in accordance with the ISO 2528 test method where the sample was placed at 23°C with an 85% RH atmosphere on one side and a desiccant on the other .

Example 5: A coating of Diofan A297 (from Solvay) in a different amount between 8 and 22 g/m2 was deposited on both sides of tracing paper having a basis weight of 62 g/m2 (from Arjowiggins). Drying was carried out at 120 °C. The following table shows the opacity index of the sheets.

Example 6: The following table shows the moisture expansiveness of two tracing papers having a basis weight of 62 g/m2, each coated with Diofan A 297 with a coating weight of 10 g/m2 and 12 g/m2. The moisture expansiveness/dimensional changes (measured along the cross grain direction) were obtained by using a Varidim apparatus, which measured the dimensional change as a function of different moisture cycles.

In the case of conventional tracing paper, the variations from peak to peak are 2.3 % (1.25 1.09, for example, in the case of the first two peaks), while in the case of tracing paper calcar coated with Diofan 16M rod, peak-to-peak variations are only 0.12% (0.15 - 0.03), which corresponds to a reduced dimensional variation by a factor of 19.

Example 7: A coating of Diofan A297 was applied to one side of three tracing papers, each having a basis weight of 42 g/m2, 102 g/m2 and 140 g/m2, using a Mayer rod. The resulting opacity is summarized as follows:

The inventors observed that the thinner the tracing paper, the less opaque the resulting paper. The thicker the coating layer, the greater the decrease in opacity.

Surprisingly, the inventors observed a very pronounced decrease in opacity that exceeded their expectations, as they managed to decrease opacity by a factor of 2.2.

Example 8: tracing paper has the following characteristics:

continuation

The water vapor transmission rate achieved in accordance with TAPPI/ANSI T 464 om-12 test method in which the test specimen was placed at 37.8°C with a 90% RH atmosphere above one side and a desiccant on the other was 96.5 g/m2/day. The opacity was 26%.

The tracing paper was coated on a roll by the smooth roll coating method. The coating layer was applied on both sides (the front side and the back side) in an amount of 4 g/m 2 per side. When the applied coating layer was a protective varnish, the water vapor transmission rate was 47.1 g/m2/day. The opacity was 20.2%.

When the applied coating layer was a dried aqueous emulsion of polyvinylidene chloride (PVDC), the water vapor transmission rate was 16.8 g/m2/day. The opacity was 24.4% and the tracing paper was repastable.

Claims (18)

1. A translucent or transparent paper comprising: (i) a fibrous substrate having a front side and a back side, the fibrous substrate comprising cellulose fibers refined to above 40°SR and the opacity index of said fibrous substrate being less than or equal to 45% measured from compliance with ISO 2471 standard; Y (ii) one or more coating layers, in particular one or two coating layers arranged on the front side of said fibrous substrate, comprising a material chosen from a material that imparts moisture barrier properties and has the ability to transparency when provided as a coating layer on said fibrous substrate and allowing the translucent or transparent paper to be repastable, said material being selected from the group comprising or consisting of vinylidene chloride copolymer or homopolymer, styrene copolymer or homopolymer, such as styrene 1,3-butadiene polymer, acrylic copolymer or homopolymer, polyester or paraffin copolymer or homopolymer, such as paraffin wax. 2. The translucent or transparent paper of claim 1, wherein one or more coating layers are also disposed on the back side of the fibrous substrate. 3. The translucent or transparent paper of claim 1 or 2 having at least one of the following characteristics or a combination thereof: (i) a hygroexpansiveness less than or equal to 1%, preferably less than or equal to 0, 5% and even more preferably less than or equal to 0.25%, when the Relative Humidity (RH) changes from 15% to 80% and then to 15% in 8 hours or (ii) a transmission rate of water vapor less than or equal to 20 g/m2/day at 85% differential RH and 23°C, or less than or equal to 10 g/m2/day at 85% differential RH and 23°C 0 less than or equal to 5 g/m2/day at 85% differential hr and 23 °C. 4. The translucent or transparent paper of any of claims 1 to 3 having an opacity index of less than or equal to 20% measured in accordance with ISO 2471. 5. The translucent or transparent paper of any of claims 1 to 4, wherein the fibrous substrate has a basis weight in a range of 40 to 200 g/m2, in particular, in a range of 40 to 140 g/m2 and preferably in a range from 40 to 90 g/m2. 6. The translucent or transparent paper of any of claims 1 to 5, wherein the fibrous substrate comprises cellulose fibers refined to 60 °SR or above 80 °SR. 7. The translucent or transparent paper of any of claims 1 to 6, wherein the fibrous substrate is a tracing paper. 8. The translucent or transparent paper of any of claims 1 to 7, wherein the total coating layer(s) on one side of the fibrous substrate has/have a dry coating weight in a range from 1 to 40 g/m2, preferably 2 to 20 g/m2, even more preferably 4 to 12 g/m2. 9. The translucent or transparent paper of any of claims 1 to 8, wherein at least one coating layer comprises a vinylidene chloride copolymer or homopolymer, in particular, a dried latex film of vinylidene chloride copolymer or homopolymer vinylidene chloride (PVDC). 10. The translucent or transparent paper of any of claims 1 to 9, wherein an ink adhesion layer is disposed on the back side of the fibrous substrate in the absence of a cover layer or an ink adhesion layer is disposed on the exposed face of the coating layer(s) which is/are provided on the rear side of the fibrous substrate, the ink adhesion layer having a thickness in a range from 0.1 to 4 µm, in particular, a ink adhesion layer comprising any of styrene acrylate, styrene butadiene, polyvinyl acetate, polyethylene acrylic acid, or modified starch or a combination thereof. 11. The translucent or transparent paper of any of claims 1 to 10, wherein at least a part of the exposed face of the ink adhesion layer or the exposed face of the coating layer disposed on the back side of the fibrous substrate comprises a printed feature, which is laterally reversed so that the feature is readable from the exposed face of the cover layer disposed on the front side of the fibrous substrate and through the fibrous substrate. 12. The translucent or transparent paper of claim 11, wherein one or more layers of white ink are disposed on the printed feature or the entire back side of the fibrous substrate comprising said printed feature. 13. A product comprising a translucent or transparent paper according to any of claims 1 to 12, wherein the translucent or transparent paper is glued to an article of paper, cardboard or light cardboard, with a layer of glue or adhesive arranged between said article of paper, cardboard or light cardboard and the layer(s) of coating or printed feature or ink layer(s) of white color on the back side of the fibrous substrate, said glue or adhesive having a thickness in a range from 2 to 12 µm, in particular, a glue or adhesive that comprises a material selected from polyurethane adhesives, acrylic adhesives, one or two component polychloroprene adhesive, polyvinyl acetate, modified starch, methyl cellulose, vinyl dispersion. 14. A process for the production of a translucent or transparent paper according to any of claims 1 to 13, comprising: a) providing or producing a fibrous substrate having a front side and a back side, wherein the fibrous substrate comprises cellulose fibers refined to above 40°SR and the opacity index of said fibrous substrate is less than or equal to 45% measured in accordance with ISO 2471; b) applying a coating composition on the front side of the fibrous substrate, the coating composition comprising a material chosen from a material that confers moisture barrier properties and has transparency capacity when provided as a coating layer on said substrate fibrous and allowing translucent or transparent paper to be repasted, said material being chosen from the group comprising or consisting of vinylidene chloride copolymer or homopolymer, such as aqueous dispersion of said vinylidene chloride copolymer or homopolymer, copolymer or homopolymer of styrene, such as aqueous dispersion of copolymer or homopolymer of styrene, such as styrene 1,3-butadiene, acrylic copolymer or homopolymer, copolymer or homopolymer of polyester, in particular water-based polyester, or paraffin, such as wax paraffin; c) drying the coating composition at a temperature between 70 and 200 °C for 0.2 to 1 minute, to form a coating layer having a thickness in a range from 1 to 40 µm, preferably from 2 to 20 µm, even more preferably from 4 to 12 jm; d) optionally, repeating Steps b) and c) at least once; Y e) optionally, also applying and drying said coating composition on the back side of the fibrous substrate at least once and/or applying and drying a composition for an ink adhesion layer on the back side of the fibrous substrate or on the/s coating layer(s) arranged on the rear side, in particular, wherein said coating composition and a composition for an ink adhesion layer are applied by a selected technique of roll-to-roll coating, knife coating, spray coating, Mayer rod coating, blow lip coating, Direct gravure, lithographic printing gravure, reverse gravure, deep coating, smooth roll coating, curtain coating, pearl coating, slot coating, double h Sm coating, film press coating, size press coating and/or transfer film method, in particular, blowing lip coating or reverse gravure coating. 15. The process of claim 14, wherein a feature is printed on the exposed side of the ink adhesion layer or the exposed side of the cover layer disposed on the back side of the fibrous substrate in reverse or mirror mode ( i.e. left/right reversal) by a selected technique of lithographic printing, inkjet printing, laser printing, xerographic printing, screen printing, flexographic printing, continuous inkjet printing, liquid toner printing, letterpress, laser engraving and/or hot foil blocking, in particular lithographic printing, ink jet printing, screen printing, continuous ink jet printing, liquid toner printing. 16. The process of claim 15, wherein one or more layers of white ink are applied over the printed feature by a selected technique of roll-to-roll coating, knife coating, spray coating, Mayer rod coating, blow lip coating, direct gravure, lithographic printing gravure, reverse gravure, deep coating, smooth roll coating, curtain coating, pearl coating, slot coating, double HSM coating, film press coating, film press coating gluing, transfer film method, lithographic printing, inkjet printing, laser printing, xerographic printing, screen printing, flexographic printing, continuous inkjet printing, liquid toner printing, hot foil blocking, especially by printing screen printing, liquid toner printing or and lithographic printing. 17. A process for the production of a product of claim 13 comprising carrying out the steps of the process according to claims 14 to 16, wherein, in addition, a layer of glue is applied on the coating layer or on the white color ink layer and/or a surface of a paper, board or light board article to bond the translucent or transparent paper and the paper, board or light board article. 18. The use of the translucent or transparent paper of claims 1 to 17 for packaging, especially luxury packaging, such as a tape, a bag, a wrapper or a substitute/alternative of transparent or translucent protective plastic laminate, wherein, Optionally, the package is heat sealed when the paper's coating layer comprises a vinylidene chloride homopolymer or copolymer, in particular, a vinylidene chloride homopolymer (PVDC).